The field of the present invention is a self contained recirculating toilet system such as those used in commercial aircraft and, in particular the recirculating pump assembly therefore.
In one prior recirculating pump assembly described in U.S. Pat. No. 3,429,445, a self cleaning filter surrounds the pump assembly. The filter includes a series of filtering slots which are cleaned by relative rotation with cleaning teeth that extend through the slots. Although the filter is effective when operative, it is complex and subject to mechanical failure. Once failure occurs the filter clogs with waste material which prevents water flow. This requires disassembly of the water pump assembly, cleaning the filter and repair of the failed parts. One solution to improve this prior art unit included installing an additional filter basket surrounding the filtering slots. But this solution is not fully satisfactory since once the filter basket clogs from waste material disassembly is again required for cleaning.
Another prior art recirculating pump assembly which attempts to overcome these problems utilizes a screen basket filter surrounding the pump assembly. The pump assembly has a housing which includes four parallel tubular members extending downward within the screen basket. One of these four tubular members is a cylindrical water powered rotating spray member. This spray member is rotated by the rinse water supply to clean the screen basket. Although this prior art pump assembly provides a spray cleaning of the screen basket it is not fully effective since portions of the screen basket which are shielded from the water spray by the other three tubular members are not cleaned. In addition the rotating spray is positioned eccentric to the axis of the screen basket whereby only the nearby portion of the screen basket which receives the full force of the spray is adequately cleaned. The other portions are only partially to inadequately cleaned.